This description relates to rowing.
Rowing is an excellent exercise that, with proper technique, uses most of the muscle groups in the rower's body and exercises more muscle groups intensively than nearly any other endurance activity.
Rowing is often a group activity for which rowers meet in a place and at a time to row in one shell or to race against each other using separate shells. When rowers row together in one shell, their motions must be synchronized. Positive group dynamics and interactions of rowers engendered by the synchronization are among the benefits of group rowing.
Live rowing of a shell on water is not only good exercise and provides stimulating interaction with other rowers, it also can offer an invigorating outdoor experience in a natural open environment. Yet rowing facilities can be expensive to use, hard to reach, or unavailable. Even when a facility is available and nearby, rowing in only one location again and again can be boring.
The biomechanics of rowing are complex. In typical live rowing of a shell on water the rower moves the handle of an oar in repeated strokes of rowing motion. Each stroke includes four successive phases sometimes called catch, drive (or power), release, and recovery. During each stroke, the rower's hands move with and impose forces on the handle of the oar. The forces vary in response to a profile of resistance (drag) imposed on the blade of the oar by the water—from almost no force to substantial pulling during the drive phase. During each stroke, the rower's seat glides back and forth on rails relative to the shell as the shell moves through the water at varying speeds.
Rowing experiences that attempt to mimic live rowing in a shell on water can be provided by stationary rowing machines. A typical rowing machine has a seat that glides back and forth on rails and a handle coupled by a chain to a mechanism that resists the rower's pulling of the handle in a profile that approximates at least part of the resistance profile characteristic of live rowing on water. Resistance mechanisms of rowing machines include air fans, water paddles, weights, hydraulics, or magnets. Rowing machines that use air fans typically have a large footprint and are noisy especially during intense rowing.